title: Glycogen levels in wildland firefighters during wildfire suppression.
abstract: OBJECTIVE
  The purpose of this project was to determine the effects of wildfire suppression on muscle glycogen utilization in wildland firefighters (WLFFs).
  
  
  METHODS
  Wildland firefighters (n = 11) participated in the study. Muscle biopsies were obtained from the vastus lateralis pre- and post-work shift. Activity patterns were measured using an Actical activity monitor positioned on the chest. Food was consumed ad libitum and recorded using a food log and interview. Differences were analyzed using paired samples t-tests and relationships were assessed using Pearson r correlation coefficients. A significance level of p < .05 was set.
  
  
  RESULTS
  Body weight was similar pre- to post-work shift (85.9 ± 9.1 and 85.6 ± 8.8 kg, respectively). Muscle glycogen decreased from pre- to post-work shift, 101 ± 7 to 80 ± 5 mmol/kg wet wt, p < .05. Average activity counts were 175 ± 60 counts/min. Mean percent of time spent in each intensity category included: sedentary (74 ± 7%), light (21 ± 5%), and moderate/vigorous (5 ± 2%). There was a significant relationship between minutes completing vigorous activity and glycogen utilization (r = -.76, p < .05), and between minutes spent completing vigorous activity and pre-shift glycogen content (r = .79, p < .05). Kilocalorie intake during the work shift was 9.2 ± 2.9 MJ/d (2195 ± 699 kcal/d).
  
  
  CONCLUSIONS
  This study demonstrates the variety of self-selected nutritional and activity habits of WLFFs, and emphasizes the relationships between moderate/vigorous activity and muscle glycogen. The current data suggest that the food provided was adequate to maintain muscle glycogen levels pre- to post-work shift.
authors.affiliation: Montana Center for Work Physiology and Exercise Metabolism, The University of Montana, Missoula, MT 59812-1825, USA.
authors.forename: John S
authors.initials: JS
authors.lastname: Cuddy
authors.forename: Dustin R
authors.initials: DR
authors.lastname: Slivka
authors.forename: Tyler J
authors.initials: TJ
authors.lastname: Tucker
authors.forename: Walter S
authors.initials: WS
authors.lastname: Hailes
authors.forename: Brent C
authors.initials: BC
authors.lastname: Ruby
mesh_terms: D002149:Energy Intake / Q000502:physiology*; D004734:Energy Metabolism / Q000502:physiology; D005247:Feeding Behavior; D005260:Female; D005390:Fires; D006003:Glycogen / Q000378:metabolism*; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism*; D016273:Occupational Exposure / Q000009:adverse effects; D009790:Occupations; D005082:Physical Exertion / Q000502:physiology*; D055814:Wilderness
chemical_list: D006003:Glycogen